LeetCode 100. Same Tree

 1 /**
 2  * Definition for a binary tree node.
 3  * struct TreeNode {
 4  *     int val;
 5  *     TreeNode *left;
 6  *     TreeNode *right;
 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 8  * };
 9  */
10 class Solution {
11 public:
12     bool isSameTree(TreeNode* p, TreeNode* q) {
13         if((p==NULL || q==NULL)&&(p!=q)){15             return false;
16         }
17         else if(p==q && p==NULL){19             return true;
20         }
21         else if(p->val==q->val){23             return isSameTree(p->left,q->left)&&isSameTree(p->right,q->right);
24         }
25         else{27             return false;
28         }
29     }
30 };